How does a right-wing conspiracy theory work? Why do Republicans insist on pursuing even obvious dead ends?

One answer to those questions is that they have a virtual army of people who are willing to push these stories relentlessly in many directions, and they know that they can sometimes get useful headlines even from misleading underlying stories.

Thus on August 21 we saw this headline on a tax blog: "The IRS Scandal, Day 1201: Larry Tribe Says 'IRS Is Engaged in Unconstitutional Discrimination Against Conservative Groups and Must Be Halted'—'Inexcusable Abuse.'"

How did a liberal lion like Harvard law professor Laurence Tribe get pulled into this mess, seeming to back up a right-wing talking point? He did so by being intellectually open-minded and generous but apparently without being aware of the underlying conspiracy theory that his words seemed to confirm. It all makes for an interesting story, requiring a bit of background.

Based on a tax code designation, what are now known as "501(c)(4) organizations" are groups that are supposed to be "operated exclusively for the promotion of social welfare."

Internal Revenue Service regulations, in what can only be described as an extremely generous reading of that statute, have defined exclusively to mean spending more than 50 percent of the organization's funds on nonpolitical activities. The rest of the money can be spent on explicitly political goals.

In the spring of 2013, what seemed like a possible scandal erupted when the treasury inspector general for tax administration (TIGTA) issued a report showing that the IRS had, for a limited period of time, sorted applications from would-be 501(c)(4) organizations by using search terms like tea party and patriot.

The relevant IRS employees had devised this method to figure out which applications were from genuine social welfare organizations versus those that were from barely disguised political groups. It later turned out that these IRS employees had also used terms with left-leaning implications, like occupy, but that never became part of the story.

Once the employees who had sorted the 501(c)(4) applications had identified the groups whose names suggested possibly inappropriate levels of political activity, they engaged in what we might now call "extreme vetting." The organizations were asked detailed questions about the sources of their finances, the content of the members' conversations at meetings and so on.

Even though one could easily imagine why each of those questions could be probative regarding the degree of a group's political activity, those questions were obviously problematic both legally and politically.

That entire approach to vetting 501(c)(4)s was, therefore, clearly wrong. It is good news, then, that when the IRS lawyers who supervised the lower-level employees found out about what was happening, they went through the steps necessary to stop it.

In other words, the TIGTA report was an autopsy. It reported that some IRS employees had done something wrong, that their superiors had stopped it and that there was no reason to think that there was any political influence involved in what had happened. But Republicans pounced, absolutely certain that the Obama White House had ordered a Nixonian abuse of IRS power.

It was obvious after the "scandal" story broke that the abandoned IRS activities were not directed by the administration, yet Republicans pressed on. A year later, even Fox News's Chris Wallace was telling a Republican congressman to, in essence, put up or shut up. Still, nothing emerged to support Republicans' claims.

More than three years on, conservatives are still trying to claim that there was a political conspiracy. Republicans in Congress have spent millions of dollars investigating these claims, while also diverting millions of dollars' worth of IRS resources to answering repetitive requests for evidence.

Despite all of this, there continues to be no evidence to support any of the conspiracy theories. So why is the story still alive, and how did Tribe end up playing a starring role for a day in this never-ending saga?

Apparently, Tribe recently (correctly) dismissed the idea of an IRS scandal as a non-scandal that has been debunked. Because Tribe is among the most well-known liberal legal scholars in the country, as well as a former adviser to Barack Obama, he is regularly trolled by right-wingers. Apparently, one or more of them took to Twitter to tell Tribe that there really is an IRS scandal.

One such response pointed Tribe to a recent decision from the U.S. Court of Appeals for the District of Columbia Circuit. Because Tribe is intellectually honest and open to being corrected, he said that he would look at the evidence.

What he found, upon reading the court's opinion, was that there had really been IRS activities that needed to be stopped. Like the IRS lawyers who had stopped the vetting program when they found out about it, Tribe was rightly shocked.

Which, of course, does not at all support the conspiracy theories that conservatives have been pushing.

No one has ever claimed that the IRS employees did nothing wrong. That was all covered in the TIGTA report, and the IRS's leadership had already ended the practice before the report was issued.

But why would Tribe's tweet be in the present tense: "IRS Is Engaged in Unconstitutional Discrimination..."? Is engaged, not was. Why did he say that the IRS "must be stopped," given that it has already stopped?

Tribe might simply have erred by not using the past tense, or he might not have realized that the activity had been stopped a long time ago. Another explanation, however, is intriguing (though equally exculpating of Tribe).

The D.C. Circuit ruled this month that a case brought by some Tea Party groups should not have been dismissed by the district court. Although the appellate court held that the Tea Party groups could not seek money damages, it held that the case was not moot and thus remanded the case for litigation of the plaintiffs' equitable claims.

Why is the case not moot, given that the IRS has long since discontinued the inappropriate vetting that caused all this trouble? The court offered two reasons, neither of which provides any sustenance to the conspiracy theorists. (The court surely pleased conservatives by saying at one point, "The IRS proudly boasts...." But beyond that bit of snark, there was nothing more.)

First, the court pointed out that, although the IRS has now appropriately processed the backlog of 501(c)(4) applications, the applications of the two plaintiff organizations in the D.C. Circuit's case are still pending. This is because the IRS has a policy of putting on hold internal reviews of cases under litigation.

Although I think the court's description of this as a Catch-22 was a bit too pat, it is nonetheless true that the IRS has not processed these two cases. Until those applications are processed, the effects of the now-abandoned procedures have not yet been completely cured.

The court's second point is that the IRS has not officially abandoned the discredited procedures. The official status of those procedures is "suspended," not "terminated permanently." As a matter of bureaucratic procedure, plenty of things that are "suspended" are effectively terminated, but in terms of invoking magic words, the court pointed out that "suspended" means that the IRS has not completely, officially ended the offensive procedures.

As a political matter, of course, it is unthinkable that the IRS would ever come close to allowing anything like this to happen again. But as a legal matter, the court correctly said that "suspended" does not mean "gone forevermore."

At this point, therefore, all the IRS has to do to make this case go away is to process the last two applications and issue a new directive putting a bureaucratic stake through the heart of the long-abandoned procedures.

This is, therefore, yet another example of how legal concepts can be misleading. Tribe (assuming that he meant to use the present tense) correctly said that the IRS "is" still doing something wrong, but only in the procedural sense that the last of the effects of the wrongdoing have not been completely cleaned up and tied off.

In the broader political context, of course, the misunderstanding of this legal nuance is more than a bit unfortunate. An important public intellectual was directed toward one tiny bit of the public record on the IRS non-scandal, and he responded to that evidence appropriately. But his words are being misused by people who want to keep the anti-Obama scandal claims alive.

To repeat: Some IRS employees did something that they should not have done. Their superiors made them stop. An inspector general reported what happened to Congress. Republicans have no evidence to show that the Obama people were involved. And Tribe is rightly dismayed that it ever happened, as are we all.